With QR code readers being installed(安装) at all(全部的) the 389 metro stations, passengers can pay(支付) their tickets(票价) via Alipay or China unioPay simply by scanning(扫描) the QR code after downloading(下载) a mobile app, the company said.

A passenger scans QR code at a metro station in east China's Shanghai, Jan. 16, 2018. Passengers can pay for their tickets via Alipay or China unioPay simply by scanning the QR code at the entrance and exit after downloading a mobile app called "Metro Daduhui(Metro大都会)". (Xinhua)

"QR codes have fundamentally changed people's daily life in China. It's the right time to roll out the new payment method, making riding the Shanghai metro more convenient," said Jin Tao, an executive with Shanghai metro information management center.

Jin told Xinhua that unlike traditional online payment, the Shanghai metro has adopted innovative technology that can function without Internet connection, taking only half a second to pass through the turnstile.

To encourage passengers to try the new payment method, the Shanghai metro will offer discounts(折扣) on fares(费用) between Jan. 20 and Feb. 28.

Currently, Shanghai has the world's longest metro network of 666 kilometers. Before spreading the QR payment service to all lines, Shanghai piloted it at two stations on the maglev line last October.